The accessing of electronic equipment by unauthorized users is a known problem. There is known method and apparatus for identifying a user through a user's input of a pre-registered identification code. For example, a user of an automated teller machine (ATM) inputs a four-digit personal identification number (PIN) using keys or buttons representing the numbers 0 to 9. Similarly many mobile devices, such as mobile phones and tablet computers are ‘locked’ and can be ‘unlocked’ by entering a similar pre-registered security code or password formed from numbers.
Such identification apparatus and methods have a security problem. For example with respect to a banking computer system a stranger can discover the PIN by surreptitiously watching the user operate the keys, and by skimming (copying the data) on the bank card the stranger can successfully identify themselves as a proper user to access the bank details of the user. Similarly with respect to a mobile apparatus, by observing the user ‘unlock’ the mobile apparatus then the device can be activated and used without the user's knowledge.
This observation can be direct, the over the shoulder or hidden camera observation, or can be indirect, for example using a thermal imaging device to observe ‘hot spots’ on the keypad or observing fingerprints caused by sweat or grease deposited on the surface when in use. Although users can attempt to obscure their fingers as they key in the code by using their other hand, or wallet as a shield, this approach is problematic as the user can often find it hard to know which button their finger is aligned with when operating the keys or buttons.
Some approaches have been proposed such as described in JP-A-2004-46548, where when a key is held down for a predetermined period to input a corresponding numeral, the numeral can be input a predetermined times during the predetermined period, and further, vibration of a vibrator notifies a user of the number of numeral inputs. Thus when the numerals in adjacent digits are entered by holding down the numeric key, it becomes difficult for a stranger to recognize, by observation of the keys or button pad alone, how often the numeral is input.
However the PIN code as implemented in JP-A-2004-46548 needs to include identical numerals in adjacent digits. This restricts PIN code flexibility in normal 4 digit codes and otherwise can cause the PIN code to become long. Furthermore although ISO standards relating to PIN codes allow codes up to 12 digits many systems do not support the entry of PIN or security codes more than 6 digits.
A further approach as discussed in US20090179779 describes where an identification code is created by combining multiple information items. One or more of multiple tactile information items that represent a created identification code are produced based on a correspondence relation between the multiple tactile information items and the multiple information units. Further, identification is performed based on determining whether the created identification code is equal to the identification code that is actually input in response to the producing of the one or more of the multiple tactile information items that represents the created identification code.